1. Field of the Invention
This invention relates to an optical system with an image stabilizing means, and more particularly to an image stabilized optical system suitable for a telescope or binoculars.
2. Description of the Prior Art
When a telescope or binoculars are supported by hands, the vibration of the hands is liable to transmit to the telescope or binoculars which results in vibration of the image viewed therethrough. Particularly when the optical instrument such as the telescope or the binoculars is carried and used in a vehicle like an aircraft or motorcar, the image is vibrated the quality of the image viewed is lowered. This is because the optical axis of the optical instrument is vibrated and the angle of the emanating optical axis is fluctuated. The vibration transmitted to the optical system is amplified by the optical system to the degree in proportion to the magnification of the optical system.
In order to avoid the vibration of the image viewed through the optical instrument or focused in an optical instrument, there have been proposed various kinds of image stabilized optical instruments. Some of these instruments are disclosed in U.S. Pat. Nos. 3,473,861, 3,608,995, and 3,608,997, and Japanese Patent Publication No. 52(1977)-23262 (U.S. Patent Appln. Ser. No. 300,528 now abandoned). These known optical systems in which the image is stabilized are very complicated in their structure. Further, most of them are of monocular type. The monocular type optical instrument is disadvantageous in that it is unstable when handled and it is not possible to see a stereoscopic view therethrough. Further, in most of these known optical instruments provided with an image stabilizing means, an optical element such as a prism or lens is mounted on a gimbal. Therefore, when the known instrument is simply applied to the binoculars having a pair of optical axes, the two optical axes cannot be always parallel to each other since they are separately stabilized by use of separate gimbals. Particularly when the optical instrument with the two optical axes which are separately stabilized is panned, it is almost impossible to make the two optical axes follow the panning to quite the same degree. Therefore, it is impossible to maintain the two optical axes always in parallel to each other, which results in deterioration in quality of the stereoscopic view observed therethrough. In addition, because of the complexity of the structure, the price and the weight of the image stabilized optical instruments is impractically very high and large.
It is also proposed to provide an optical instrument of binocular type equipped with an image stabilizing means as disclosed in U.S. Pat. Nos. 2,829,557 and 2,939,363. These optical instruments of binocular type are incomplete in principle to stabilize the image. Therefore, the image is not sufficiently stabilized, and further, the optical system and the mechanical structure thereof are both very complicated.